Lock valve



R. E. BAUER LOCK VALVE June 3, 1958 Filed Feb. 18, 1955 2 M m E m g y a Z United States Patent LOCK VALVE. Russell E. Bauer, Grosse Pointe Woods, Mich. Application February 18, 1955, Serial No. 489,227

Claims. 1 or. 137-106) The present invention relates generally to. lock valves of the type utilized to control the admission to and withdrawal of hydraulic fluid from hydraulically-operated devices. More specifically, this invention relates to a lock valve for controlling the admission to and withdrawal of hydraulic fluid from a gun elevating and depressing cylinder.

The present application is a continuation-in-part of my copending application S. N. 330,871 filed January 12, 1953 which discloses a spool-type lock valve employed in a hydraulic control system of a gun mounted in the turret of a military tank, The lock valve shown in the above-mentioned application is a double valve having two spring-centered spools, one spool controlling the admission and return of fluid from the automatic controls system and the other controlling the admission and return of fluid from the manual control system. Each of the spools simultaneously admits fluid to the one end of the elevating cylinder while permitting escape of a like amount of fluid from the other end.

In hydraulically-operated devices it is conventional t dispose a check valve or valves in the lines which conduct hydraulic fluid into and out of the device. In hydraulic cylinders and other hydraulically-operated devices subject to shock, such as is the case. with a tank gun elevating cylinder, ordinary check valves have not been effective to prevent movement of the elevating cylinder when the tank itself is moving and oil is not beingpumped. When a stationary gun having an ordinary check or lock valve is bounced up and down over rough terrain the elevating cylinder has exhibited a pumping action or transfer of oil to one end of the cylinder, resulting in undesirable, build-up of pressure therein. Also, check valves'have not protected the tank oil supply lines against impact pressures when the tank is moving and oil is being pumped. When the tank bounces and bumps over rough terrain while the gun is being raised or lowered, ordinary check valves have not protected the open supply lines against momentary high pressures induced'by the reaction of the heavy length of gun barrel. Likewise, check valves have not beenas effective as desired to prevent movement of the gunwhen the tank is stationary and the supply valves are closed. This has usually re-.

sulted in a slow elevation or depression of the gun while standing for any length of time.

It is an object, therefore, to provide a lock valve which will positively prevent iii-leakage and outflow of oil from a hydraulically-operated device when the oil supply lines are closed.

It is also an object of this invention to provide a lock valve which will elficiently protect a hydraulic supply system against shock induced by momentary impacts applied to the controlled device when the supply lines are open. g

It is another object to provide a lock valve which will permit a hydraulic cylinder to move only when oil is being pumped.

Another object is to provide a lock valve which will "ice provide control of hydraulic fluid in a gun-control, which lock valve is sufficiently sensitive to pass and retain even minute amounts of fluid supplied thereto by highly sensitive hydraulic displacement control devices.

Other objects and advantages of the present invention will be apparent, or will become apparent in the more detailed description of the invention to follow including a description of the accompanying drawings,'wlierein:

Fig. l is a transverse elevational view in section of the lock valve of this inventionshowing one valving element and its accessory parts, the section being taken along the line 11 of Fig. 2;

,Fig. 2 is a bottom view of a three-way valve of this invention showing the pairs of adapter fittings for the entrance and exit lines for each valving element and also showing the details of the valve body housing; and

Fig. 3'is a side view in elevation of the lock valve of Figs. 1 to 3.

In accordance with this invention a spool-type lock valve is provided having a precision check valve element, preferably a ball check element, in the fluid delivery side of the spool is order to control the direction of flow through the valve and a pressure equalizing means on the fluid inlet side of the spool to assist the latter in centering itself when-fluid is not being pumped. The check'valve element combines with the spool valve elementto prevent movement in the hydraulically-operated device, except when oil is being pumped (i. e. when the control valve or valves are open), to protect the oil supply lines against impact when the control valves are open, and to prevent movement in the hydraulicallyoperated device when the control valves are closed. The pressure equalizing means likewise aids in preventing movement of the'hydraulicallywperated device by permitting the pressures on the inlet and outlet sides of the spool to equalize after closure of the main control valve, thereby causing the spool to more quickly and efliciently re-center itself in the closed position. The equalizer means may be a passageway, preferably having a precision flow controlling device therein which permits a slow controlled leakage therethrough to balance the pressure on the spool lands when the latter is in the fully closed position yet which does not result in appreciable loss of fluid during operating cycles.

Referring now to the drawings, and particularly to Fig. 1 thereof, it will be seen that the valve of .this invention comprises a metal body section 10 and two metal end plates 12 secured thereto by countersunk bolts 14 which are provided with lock washers 16. Also provided are vertical bolt holes 17 for suitably mounting the valve body 10. Bored transversely through body portion 10 are three valve passageways 18 in each of which is disposed an annular sleeve-like valve element 20. The three sets of valves thus provided can be used to control different functions or control separate circuits of the same or different double-acting hydraulic devices, as for example, the automatic, manual and super-elevation control circuits of a tank gun control system. Inside each sleeve 20 is a slideable valve spool 22 having on each end a longitudinal end passageway 23 communicating with annular grooves or undercuts 24, 26 through transverse passageways 25. A seal between each end of sleeve 20 and the end plates 12 is provided by means of O-ring seals 28. In each end plate 12 there is a spring-retainer chamber 30 in which is disposed a spring retainer cup 32 and a compression spring 34 confined between cup 32 and the bottom of chamber 30. Each of the retainer cups 32 is in contact with the end of a spool 22 and is free to move only outwardly with respect to the sleeve 20 when the spool is moved in that direction from its center position. 30 through passageways 23, 25 operates to move the spool in either direction, as will be more fully explained below,

Oil entering chamber Bored vertically in the bottom of body section so as to intersect each transverse valve passageway 18 are a pair of fluid line ports or passageways 36, 38. Adapter fittings 40, are screwed into each of passageways 36, 38 tov permit easy connection to hydraulic lines. The sleeve 2tl'likewise has on one end an annular groove 42 in which is bored a transverse passageway 44, the groove 42 being so positioned on sleeve as to communicate directly with bottom body inlet-outlet passageway 36. Likewise, another annular groove 46 and a transverse passageway 48 are so located in the other end of sleeve as to communicate directly with bottom body inlet-outlet passageway 38. Passageway 44 communicates directly with the spool groove 24 while passageway 48 communicates with the spool groove 26.

Above the transverse valve passageways 18 the valve body 10 is bored transversely from each side to provide a ball check valvechamber 50 and a fluid delivery passage-. way 52. Connecting with each of the latter is a vertical passageway 54 which is plugged at its outer end at 56. Each ball check chamber 50 also is provided with a vertical load port or fluid delivery passageway 58 which leads out of the'valve body. Each passageway 54 and its associated passageway 52 constitute part of an inlet flow path or fluid charging route leading to its associated load port or passageway 58. Each passageway 58 also serves as a direct connection to the spool for exhaust or low pressure fluid flowing in the opposite direction. The intersection between each of the passageways 50, 52 forms a valve seat 60 in which is seated a precision fitted steel.

ball 62 which is held in place by a guide 64 integral with a guide pin 66, the latter being fitted loosely in a hole 68 in end plate 12. A spring 70 urges the guide pin 66 and guide 64 into contact with the ball 62 to firmly seat it in the valve seat 60. Other types of check valve elements can be employed, if desired.

The sleeves 20 are each provided with annular grooves 72, 74, 76 and 78; groove 72 being adapted to communicate through a transversely bored hole 80 with the groove 24 of the spool 22 when the spool is moved to the right as viewed in Fig. 1, groove 74 communicating with groove 24 in a similar fashion through a transverse hole 82 when the spool is moved to the left, groove 76 communicating with spool groove 26 through hole 84 when the spoolis moved to the right and groove 78 communicating with spool groove 26 through hole 86 when the spool is moved to the left.

Below sleeve valve passageways 18, passageways 36, 38

are connected by a small transverse passageway 88 in L which is inserted pin 90 having a diameter slightly smaller than passage 88, or other metering device, which will permit the desired rate of leakage or seepage between passageways 36, 38. The pin 90 is held in place by a plug 92' having an O-ring seal 94. The plug 92 in .turn is retained by the end plate 12. The function of passageway 88 will be more fully described below.

The lock valve is shown in the drawings in the closed or locked position in which it will not permit flow or leakage of fluid in either direction. For purposes of illustration, let it be assumed that the right-hand passageway 58 (as viewed in Fig. 1) is connected to the bottom end A of a hydraulic cylinder and that the left-hand passageway 58 is connected to the upper end B of the same cylinder. Let it also be assumed that the fitting in passageway 36 is connected tothe up control valve and that passageway 38 is connected to thedown controlvalve. In this situation, let it be assumed that it is first desired to raise the controlled piston. To do this, the up control valve is opened to admit highpressure fluid through 'passageway 36. When this is done, fluid enters spool'groove 24 through passageway 36, sleeve groove 42, andsle'eve" hole 44. Oil flows from groove 24 through passageways 23, 25 into theright-hand spring chamber 30 to cause spool 22 to move to the left until" the right-hand .edge' of 4 central spool land clears the edge of sleeve passageway 82 thereby permitting the fluid in groove 24 to flow through passageway 82 and up right-hand passageways 54 and 52, thereby unseating the associated or left-hand ball 62 so that the fluid can pass through chamber 50 and out of the valve body through delivery passageway 58. The flow path thus described is an inlet flow path from the line port or passageway 36 to its associated delivery port or passageway 58. The mentioned edge on the central spool land 100 defines with the sleeve passageway 82 a variable inlet restriction in this inlet flow path which meters the flow of pressure fluid to its associated check valve. This same leftward movement of spool 22 causes the inner edge of left-hand spool land 102 to open passageway 86 to permit escape of fluid from the upper end of the controlled piston through left-hand load port or passageway 58, chamber 50, behind the left-hand check valve to groove 26 through sleeve passageway 86 and thence through the line port or passageway 38 out of the valve to the control valve and thence to the reservoir or inlet side of the fluid pump. The flow path last described is an exhaust flow path from the left-hand load port or passageway 58 to its corresponding line port or passageway 38. The mentioned edge on the left-hand spool land 102 defines with the sleeve passageway 86 a variable outlet restriction in this exhaust flow path which meters the flow of exhaust fluid from its associated load port or passageway S8to its associated line port or passageway 38. Thus, the lock valve of this invention simultaneously permits flow through the valve body of pressure fluid in an inlet flow path in one direction and of exhaust fluid in an exhaust flow path in.the opposite direction when the oil pressure on the inlet lines 36, 38 dilfers.

When the up controlvalve is shut oil, the spool 22 high pressure oil is present between the closed control valve and the spool. The oil from right-hand chamber 30, therefore, normally would have no place to go. In the valve of this invention, however, the equalizer passageway 88 permits the high pressure oil to slowly leak across to line 38 until the pressures in lines 36, 38 are equal. The return movement to the right of the spool will displace oil from the right-hand chamber 30 and cause a likeamount of oil to enter the left-hand chamber 30 from line38. This equalizing oil is supplied to line 38 by leakage through equalizer passage 88. When the pressuresin lines 36, 38 are fully equalized the springs 34 will have returned spool 22 to its centered closed position. A static load or shock on the extended or raised piston will be taken on the right-hand ball check element62. The check element 62 and the spool 22 positively prevent out leakage from the up end of the cylinder. Moreover, the ball check element 62 positively prevents backward flow of oil .(when spool 22 is open) caused by an impact load suddenly imposed on the rising piston. When the spool has reecentered itself, oil can not be pumped into either end of the extended cylinder when thecylinder is bounced under loadwith the control valves closed.

When it is desired to lower the piston, the down control valve is opened admitting high pressure fluid to passageway 38. Thiscauses oil to enter the left-hand spring chamber 30 and the spool 22to move to the right until the left-hand edge of central spool land 100 clears the edge of passageway 84, fluid therebybeing admitted therethrough from groove 26 into left-hand passageway 54, through left-hand passageway 52 to unseat the lefthand ball check valve 62' and permit flow of fluid to the upper endB of'the controlled cylinder through chamber 50 and left-hand load port or passageway 58. The

asamo flow path thus described is another inlet flow path this time from the line port or passageway 38 to its associated left-hand load port or passageway 58. The mentioned edge on the center spool end 100 defines with the sleeve passageway 84 a variable inlet restriction in this other inlet flow path which meters the flow of pressure fluid to its associated check valve. In the down cycle, fluid is simultaneously forced from the lower end of the cylinder since the right-hand movement of the spool causes the inner edge of right-hand land 104 to connect sleeve passageway 80 across line port or passageway 36 and righthand load port or passageway 58 through spool groove 24. This allows fluid to pass downward through righthand load port or passageway 58 behind the right-hand check valve and out of line port or passageway 36 and return through the control valve to the reservoir or to the pump. The path thus described is another exhaust flow path this time from the right-hand load port or passageway 58 to its corresponding line port or passageway 36. The mentioned edge on the right-hand spool land 104 defines with the sleeve passageway 80 a variable outlet restriction in this other exhaust flow path which meters the flow of exhaust fluid from its associated load port or passageway 58 to its associated line port or passageway 36. On the down cycle, the left-hand check valve 62 also functions to control the direction of flow through the lock valve and protect the spool and supply lines against resistance or shock pressures imparted to the moving piston. After the down control valve closes, the passageway 88 permits leakage from line 38 to line 36' to again balance the pressure exerted by the spool chamber 30 and allow the springs 34 to re-center the spool.

What is claimed is:

1. A lock valve for use with a reversible hydraulic load device comprising a housing having two line ports and a load port corresponding to each line port, first means defining an inlet flow path from each line port to its corresponding load port, said first means including a check valve in each inlet flow path directed to prevent flow from its associated load port to its associated line port, said first means also including a variable inlet restriction in each inlet flow path between the check valve therein and its associated line port to meter the fiow to said check valve, second means defining an exhaust flow path coexistent with and independent of each of said inlet flow paths from each load port to its corresponding line port, said second means including a variable outlet restriction in each exhaust path to meter the flow from its associated load port to its associated line port, said second 6 means directing the flow in each exhaust path to its corresponding line port behind the check valve associated with the same line port, a displaceable member having a centered position closing off the inlet restriction in each of said inlet flow paths and the outlet restriction in each of said exhaust flow paths, the movement of said displaceable member being responsive to the difierence in pressures in said two line ports for varying the area of and flow through the inlet restriction in the inlet flow path leading from the line port of higher pressure and correspondingly varying the area of and flow through the outlet restriction in the exhaust path leading to the line port of lower pressure and for closing off the flow through the outlet restriction in the other exhaust flow path and the inlet restriction in the other inlet flow path.

2. A lock valve as definid in claim 1 wherein the displaceable member is a valve spool provided with lands and the housing has a bore therein that intersects each of said inlet flow paths and said exhaust flow paths at a diiferent point along its aXis, and further including a sleeve fixed in said bore for slidably carrying said valve spool, and wherein each variable restriction is defined by a passageway in the sleeve and an edge on one of the lands on the valve spool.

3. A lock valve as defined in claim 2 wherein yieldable centering means are provided for centering the valve spool, and further including means defining chambers one on each end of the valve spool, and passageway means connected the chambers individually each to one of said two line ports.

4. A lock valve as defined in claim 1 wherein equalizing means are provided to equalize the pressure in said two line ports upon cutofi of pressure fluid to the line port of higher pressure thereby equalizing the pressure in said chambers in aid of the action of said yieldable means in centering the valve spool.

5. A lock valve as denfied in claim 4 wherein said equalizing means includes a passageway interconnecting said two line ports and a flow restrictor in the equalizing passageway.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,312 Clay Sept. 27, 1949 2,500,555 Majneri Mar. 14, 1950 2,608,986 Stephens Sept. 2, 1952 2,648,346 Deardorfi et al. Aug. 11, 1953 

